In general, an ink-jet recording apparatus (an example of liquid jetting apparatus) comprises: a recording head (head member) having nozzles, jetting-driving means (for example, piezoelectric vibrating members or heating elements) for jetting ink (liquid) from the nozzles, and jetting controller for controlling the jetting-driving means based on recording data. Supply of the ink to the nozzles is conducted by an ink cartridge (ink container) and ink ways that extend from the ink cartridge to the nozzles. The ink cartridge is usually replaceable.
Basically, recording quality by the ink-jet recording apparatus depends on resolution of the recording head that is defined by a size (diameter) of each of the nozzles and the number of nozzles. In addition, the recording quality may be affected by the kind of ink, viscosity of the ink, blur of the ink on a recording medium, and so on.
For example, since the ink in the nozzles of the recording head is exposed to air, solvent of the ink such as water may gradually evaporate. This may increase a viscosity of the ink in the nozzles, so that quality of recorded images may deteriorate. Thus, in the ink-jet recording apparatus, in order to prevent the viscosity of the ink in the nozzles from increasing, some volume of the ink is absorbed from the nozzles (cleaning operation) or some volume of the ink is jetted from the nozzles not to form any dot on the recording medium (flushing operation).
Especially, when the ink cartridge is replaced with another new ink cartridge, the cleaning operation or the flushing operation is conducted until supply of the ink from the new ink cartridge to the nozzles becomes stable.
In addition, if the ink in the ink cartridge is running short, it may become difficult for the ink to be smoothly jetted so that recording quality may deteriorate. Thus, a timing when a volume of the ink remaining in the ink cartridge becomes less than a predetermined volume is judged as a ink end, so that an indication for requesting replacement of the ink cartridge is conducted.
However, pigment ink is used as ink having a great light-resistance. The pigment ink may consist of pigment, dispersants, solvent and additives. Especially, it is preferable that the pigment ink has a great resistance to ultraviolet-ray.
In general, the ink cartridge contains the pigment ink by containing a foam material filled (impregnated) with the pigment ink. In the ink cartridge, if a long time has passed since the ink cartridge was manufactured, dispersion of the pigment may deteriorate and the pigment may sink because of gravity. In the case, density of the ink at a base portion (at a ink supplying port side) of the ink cartridge become higher, and density of the ink at an upper portion of the ink cartridge become lower.
In order to improve such unevenness of the density of the ink, it is effective to stir the ink contained in the ink cartridge. However, it is difficult to provide any stirring mechanism for the ink cartridge containing the foam material.